1. Field of the Invention
The present invention relates to a transmission method for aggregating a voice frame and a non-voice frame and transmitting and receiving them in a wireless Local Area Network (LAN) Medium Access Control (MAC) layer.
2. Description of the Related Art
Widespread use of the Internet and increasing demand among users for multimedia services such as voice and video services, in addition to data services, is driving up demand for real-time quality assurance for stable provision of multimedia services. Especially, Voice over Internet Protocol (VoIP) for providing voice services using the Internet is an application that requires more real-time quality assurance for the services, because VoIP has a high sensitivity to delay and jitter compared to data and images.
Meanwhile, wireless LANs, which have the advantages of convenient installation and mobility, have been widely deployed since the mid-1990s and widely used in recent years as they offer a transfer rate close to the 100 Mbps of a wired LAN. Besides, mobility and reduction of usage fees can be achieved due to a combination of wireless LAN and VoIP.
The Institute of Electrical and Electronics Engineers (IEEE) developed a standard that defines a protocol for transmission of data frames between a Wireless LAN station and an Access Point (AP). As a result, the IEEE established a standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications (IEEE 802.11-PHY/MAC) in 1999, and afterwards established a standard for supporting Quality of Service (QoS) in a MAC layer (IEEE 802.11e) in 2005.
The IEEE 802.11 Wireless LAN standard describes a mobile station and a fixed AP as the two principal elements of a Wireless LAN. A single cell using the IEEE 802.11 WLAN standard is defined as a Basic Service Set (BSS), and a multiple cell is defined as an Extended Service Set (ESS). Each station and each AP implements a MAC layer having a function enabling exchange of MAC frames. The MAC frame is used as a medium for management, control, and data transmission between a wireless station and an AP. An efficient method of transmitting and receiving a MAC frame, especially, a voice frame is required in order to achieve reliable provision of voice services sensitive to delay.